The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Lajos Hanzo - One of the best experts on this subject based on the ideXlab platform.

  • fractional Frequency Reuse aided twin layer femtocell networks analysis design and optimization
    IEEE Transactions on Communications, 2013
    Co-Authors: Rong Zhang, Lajos Hanzo
    Abstract:

    Femtocells constitute an economical solution conceived for improving the indoor coverage, which are capable of achieving a high network capacity. In order to guarantee a high Spectral Efficiency (SE), femtocells have to Reuse the spectrum of macrocells. As a result, the performance of both the femtocells and macrocells may suffer owing to the near-far effects. In this paper, we study a twin-layer cellular networks, where the Macrocell Base Stations (MBSs) employing Fractional Frequency Reuse (FFR) host the Femtocell Base Stations (FBSs). This paper investigates the design, performance analysis and optimization problems of this FFR aided twin-layer network. We firstly assume that the femtocells opt for full spectrum access (FSA). The per-layer outage probability (OP) is derived and the network is optimized for maximizing the macrocell's throughput. We found that the advantage of FFR eroded in dense femtocell-scenarios and the optimized network tends to become a Unity Frequency Reuse (UFR) aided system. We then propose a spectrum swapping access (SSA) strategy for protecting the macrocell's performance and for overcoming the typical near-far problem. Our analysis demonstrates that both the OP of femtocell users in the Cell Centre Region (CCR) and that of the macrocell users in the Cell Edge Region (CER) will be reduced by the proposed SSA. The optimized network using our SSA is more robust to the detrimental impact of femtocells.

  • fractional Frequency Reuse aided twin layer femtocell networks analysis design and optimization
    IEEE Transactions on Communications, 2013
    Co-Authors: Rong Zhang, Lajos Hanzo
    Abstract:

    Femtocells constitute an economical solution conceived for improving the indoor coverage, which are capable of achieving a high network capacity. In order to guarantee a high Spectral Efficiency (SE), femtocells have to Reuse the spectrum of macrocells. As a result, the performance of both the femtocells and macrocells may suffer owing to the near-far effects. In this paper, we study a twin-layer cellular networks, where the Macrocell Base Stations (MBSs) employing Fractional Frequency Reuse (FFR) host the Femtocell Base Stations (FBSs). This paper investigates the design, performance analysis and optimization problems of this FFR aided twin-layer network. We firstly assume that the femtocells opt for full spectrum access (FSA). The per-layer outage probability (OP) is derived and the network is optimized for maximizing the macrocell's throughput. We found that the advantage of FFR eroded in dense femtocell-scenarios and the optimized network tends to become a Unity Frequency Reuse (UFR) aided system. We then propose a spectrum swapping access (SSA) strategy for protecting the macrocell's performance and for overcoming the typical near-far problem. Our analysis demonstrates that both the OP of femtocell users in the Cell Centre Region (CCR) and that of the macrocell users in the Cell Edge Region (CER) will be reduced by the proposed SSA. The optimized network using our SSA is more robust to the detrimental impact of femtocells.

Rong Zhang - One of the best experts on this subject based on the ideXlab platform.

  • fractional Frequency Reuse aided twin layer femtocell networks analysis design and optimization
    IEEE Transactions on Communications, 2013
    Co-Authors: Rong Zhang, Lajos Hanzo
    Abstract:

    Femtocells constitute an economical solution conceived for improving the indoor coverage, which are capable of achieving a high network capacity. In order to guarantee a high Spectral Efficiency (SE), femtocells have to Reuse the spectrum of macrocells. As a result, the performance of both the femtocells and macrocells may suffer owing to the near-far effects. In this paper, we study a twin-layer cellular networks, where the Macrocell Base Stations (MBSs) employing Fractional Frequency Reuse (FFR) host the Femtocell Base Stations (FBSs). This paper investigates the design, performance analysis and optimization problems of this FFR aided twin-layer network. We firstly assume that the femtocells opt for full spectrum access (FSA). The per-layer outage probability (OP) is derived and the network is optimized for maximizing the macrocell's throughput. We found that the advantage of FFR eroded in dense femtocell-scenarios and the optimized network tends to become a Unity Frequency Reuse (UFR) aided system. We then propose a spectrum swapping access (SSA) strategy for protecting the macrocell's performance and for overcoming the typical near-far problem. Our analysis demonstrates that both the OP of femtocell users in the Cell Centre Region (CCR) and that of the macrocell users in the Cell Edge Region (CER) will be reduced by the proposed SSA. The optimized network using our SSA is more robust to the detrimental impact of femtocells.

  • fractional Frequency Reuse aided twin layer femtocell networks analysis design and optimization
    IEEE Transactions on Communications, 2013
    Co-Authors: Rong Zhang, Lajos Hanzo
    Abstract:

    Femtocells constitute an economical solution conceived for improving the indoor coverage, which are capable of achieving a high network capacity. In order to guarantee a high Spectral Efficiency (SE), femtocells have to Reuse the spectrum of macrocells. As a result, the performance of both the femtocells and macrocells may suffer owing to the near-far effects. In this paper, we study a twin-layer cellular networks, where the Macrocell Base Stations (MBSs) employing Fractional Frequency Reuse (FFR) host the Femtocell Base Stations (FBSs). This paper investigates the design, performance analysis and optimization problems of this FFR aided twin-layer network. We firstly assume that the femtocells opt for full spectrum access (FSA). The per-layer outage probability (OP) is derived and the network is optimized for maximizing the macrocell's throughput. We found that the advantage of FFR eroded in dense femtocell-scenarios and the optimized network tends to become a Unity Frequency Reuse (UFR) aided system. We then propose a spectrum swapping access (SSA) strategy for protecting the macrocell's performance and for overcoming the typical near-far problem. Our analysis demonstrates that both the OP of femtocell users in the Cell Centre Region (CCR) and that of the macrocell users in the Cell Edge Region (CER) will be reduced by the proposed SSA. The optimized network using our SSA is more robust to the detrimental impact of femtocells.

Jinglin Shi - One of the best experts on this subject based on the ideXlab platform.

  • adaptive soft Frequency Reuse scheme for wireless cellular networks
    IEEE Transactions on Vehicular Technology, 2015
    Co-Authors: Manli Qian, Wibowo Hardjawana, Branka Vucetic, Xuezhi Yang, Jinglin Shi
    Abstract:

    Spectrum scarcity and intercell interference (ICI) are two fundamental limiting factors in wireless cellular systems. Soft Frequency Reuse (SFR) has been proposed as an effective way to manage the spectrum and reduce ICI in cellular systems. In a static SFR scheme, the allocations of transmit power or subcarriers in each cell are fixed prior to system deployment. This limits the potential performance of the SFR scheme. In this paper, we propose an intercell resource-allocation algorithm, which is referred to as the adaptive SFR algorithm (ASFR), that dynamically optimizes subcarrier and power allocations for multicell wireless networks to improve system capacity. The ASFR first finds the subcarrier and power allocations in each cell by using exhaustive search and greedy descend methods and then iteratively repeats among cells until a predefined convergence criterion is satisfied. The theoretical analysis proves the convergence of the ASFR algorithm. Simulation results show that the ASFR achieves a higher system throughput and better cell edge user performance than existing Frequency Reuse schemes.

  • inter cell interference coordination through adaptive soft Frequency Reuse in lte networks
    Wireless Communications and Networking Conference, 2012
    Co-Authors: Manli Qian, Wibowo Hardjawana, Branka Vucetic, Jinglin Shi, Xuezhi Yang
    Abstract:

    In 3GPP Long Term Evolution (LTE) networks, the Frequency Reuse schemes such as fractional Frequency Reuse (FFR) and soft Frequency Reuse (SFR) are used to improve system capacity. The allocation of transmit power and subcarriers to each cell in these schemes are fixed prior to network deployment. This limits the potential performance of these Frequency Reuse schemes. In this paper, we propose to improve the capacity of SFR scheme by jointly optimizing subcarrier and power allocation in multi-cell LTE networks. An iterative algorithm that can adaptively vary the number of major subcarriers and adjust the transmit power for each cell according to wireless traffic loads is proposed. Simulation results show that the proposed algorithm outperforms the existing Reuse 1, FFR and static SFR schemes in both system throughput and cell edge user performance.

Xuezhi Yang - One of the best experts on this subject based on the ideXlab platform.

  • adaptive soft Frequency Reuse scheme for wireless cellular networks
    IEEE Transactions on Vehicular Technology, 2015
    Co-Authors: Manli Qian, Wibowo Hardjawana, Branka Vucetic, Xuezhi Yang, Jinglin Shi
    Abstract:

    Spectrum scarcity and intercell interference (ICI) are two fundamental limiting factors in wireless cellular systems. Soft Frequency Reuse (SFR) has been proposed as an effective way to manage the spectrum and reduce ICI in cellular systems. In a static SFR scheme, the allocations of transmit power or subcarriers in each cell are fixed prior to system deployment. This limits the potential performance of the SFR scheme. In this paper, we propose an intercell resource-allocation algorithm, which is referred to as the adaptive SFR algorithm (ASFR), that dynamically optimizes subcarrier and power allocations for multicell wireless networks to improve system capacity. The ASFR first finds the subcarrier and power allocations in each cell by using exhaustive search and greedy descend methods and then iteratively repeats among cells until a predefined convergence criterion is satisfied. The theoretical analysis proves the convergence of the ASFR algorithm. Simulation results show that the ASFR achieves a higher system throughput and better cell edge user performance than existing Frequency Reuse schemes.

  • a multilevel soft Frequency Reuse technique for wireless communication systems
    IEEE Communications Letters, 2014
    Co-Authors: Xuezhi Yang
    Abstract:

    A multilevel soft Frequency Reuse (ML-SFR) scheme and a resource allocation methodology are proposed for wireless communication systems. In the proposed ML-SFR scheme, there are $2\hbox{N}$ power density limit levels, achieving a better interference pattern and further improving the cell edge and the overall data rate compared with the traditional two-level SFR scheme. The detailed design of an eight-level SFR scheme is demonstrated. Numerical results show that the cell-edge spectrum efficiency is increased to five times of that of Reuse 1, and the overall spectrum efficiency is improved by 31%. The ML-SFR can be utilized in the current 4G system and would be a candidate key technology for future 5G systems.

  • inter cell interference coordination through adaptive soft Frequency Reuse in lte networks
    Wireless Communications and Networking Conference, 2012
    Co-Authors: Manli Qian, Wibowo Hardjawana, Branka Vucetic, Jinglin Shi, Xuezhi Yang
    Abstract:

    In 3GPP Long Term Evolution (LTE) networks, the Frequency Reuse schemes such as fractional Frequency Reuse (FFR) and soft Frequency Reuse (SFR) are used to improve system capacity. The allocation of transmit power and subcarriers to each cell in these schemes are fixed prior to network deployment. This limits the potential performance of these Frequency Reuse schemes. In this paper, we propose to improve the capacity of SFR scheme by jointly optimizing subcarrier and power allocation in multi-cell LTE networks. An iterative algorithm that can adaptively vary the number of major subcarriers and adjust the transmit power for each cell according to wireless traffic loads is proposed. Simulation results show that the proposed algorithm outperforms the existing Reuse 1, FFR and static SFR schemes in both system throughput and cell edge user performance.

Jeffrey G Andrews - One of the best experts on this subject based on the ideXlab platform.

  • analytical evaluation of uplink fractional Frequency Reuse
    IEEE Transactions on Communications, 2013
    Co-Authors: Thomas David Novlan, Jeffrey G Andrews
    Abstract:

    The design and evaluation of Inter-cell Interference Coordination (ICIC) techniques has been the focus of significant research as wireless networks are increasingly faced with the challenge of balancing fairness to users at the cell-edge with high spectral efficiency. This work considers the use of Fractional Frequency Reuse (FFR), in the cellular uplink, which is well-suited for modern cellular networks due to its low complexity and coordination requirements and resource allocation flexibility. These approaches have typically been modeled using deterministic grids for the base station deployments and analyzed through system-level simulations, which do not lead to fundamental insights or tractable expressions of relevant metrics of coverage probability or average rate for a typical user. Instead, this work utilizes Poisson point processes for the underlying spatial models for user and base station locations. From the derived expressions we quantify the coverage gains with Strict FFR relative to universal Reuse and Soft Frequency Reuse (SFR), as well as the performance tradeoff SFR achieves for edge and inner users through greater bandwidth efficiency. We additionally illustrate how the analytical model can be directly related to traffic or coverage requirements and gives insight into selecting power control parameters and resource allocations under Strict FFR and SFR to achieve system capacity gains over universal Frequency Reuse.

  • analytical evaluation of fractional Frequency Reuse for heterogeneous cellular networks
    arXiv: Information Theory, 2011
    Co-Authors: Thomas David Novlan, Radha Krishna Ganti, Amitava Ghosh, Jeffrey G Andrews
    Abstract:

    Interference management techniques are critical to the performance of heterogeneous cellular networks, which will have dense and overlapping coverage areas, and experience high levels of interference. Fractional Frequency Reuse (FFR) is an attractive interference management technique due to its low complexity and overhead, and significant coverage improvement for low-percentile (cell-edge) users. Instead of relying on system simulations based on deterministic access point locations, this paper instead proposes an analytical model for evaluating Strict FFR and Soft Frequency Reuse (SFR) deployments based on the spatial Poisson point process. Our results both capture the non-uniformity of heterogeneous deployments and produce tractable expressions which can be used for system design with Strict FFR and SFR. We observe that the use of Strict FFR bands reserved for the users of each tier with the lowest average SINR provides the highest gains in terms of coverage and rate, while the use of SFR allows for more efficient use of shared spectrum between the tiers, while still mitigating much of the interference. Additionally, in the context of multi-tier networks with closed access in some tiers, the proposed framework shows the impact of cross-tier interference on closed access FFR, and informs the selection of key FFR parameters in open access.

  • coverage in two tier cellular networks with fractional Frequency Reuse
    Global Communications Conference, 2011
    Co-Authors: Thomas David Novlan, Radha Krishna Ganti, Jeffrey G Andrews
    Abstract:

    Fractional Frequency Reuse (FFR) is an interference management technique well-suited to OFDMA-based cellular networks wherein the cells are partitioned into spatial regions with different Frequency Reuse factors. These techniques are of further relevance when considered in the context of heterogeneous networks whose performance is often limited by intercell and inter-tier interference. To date, FFR techniques have typically been evaluated through system-level simulations using a hexagonal grid for the base station locations. This paper instead focuses on analytically evaluating the two main types of FFR deployments - Strict FFR and Soft Frequency Reuse (SFR) - using a Poisson point process to model the access point locations. Under reasonable assumptions for modern cellular networks, our results reduce to tractable expressions which provide insight into system design guidelines and the relative merits of Strict FFR and SFR, compared to universal Reuse for a two-tier network with open access between tiers.

  • a new model for coverage with fractional Frequency Reuse in ofdma cellular networks
    Global Communications Conference, 2011
    Co-Authors: Thomas David Novlan, Jeffrey G Andrews, Radha Krishna Ganti, Arunabha Ghosh
    Abstract:

    Fractional Frequency Reuse (FFR) is an interference management technique well-suited to OFDMA-based cellular networks wherein the cells are partitioned into spatial regions with different Frequency Reuse factors. To date, FFR techniques have been typically been evaluated through system-level simulations using a hexagonal grid for the base station locations. This paper instead focuses on analytically evaluating the two main types of FFR deployments - Strict FFR and Soft Frequency Reuse (SFR) - using a Poisson point process to model the base station locations. The results are compared with the standard grid model and an actual urban deployment. Under reasonable special cases for modern cellular networks, our results reduce to simple closed-form expressions, which provide insight into system design guidelines and the relative merits of Strict FFR, SFR, universal Reuse, and fixed Frequency Reuse.

  • analytical evaluation of fractional Frequency Reuse for ofdma cellular networks
    arXiv: Information Theory, 2011
    Co-Authors: Thomas David Novlan, Radha Krishna Ganti, Arunabha Ghosh, Jeffrey G Andrews
    Abstract:

    Fractional Frequency Reuse (FFR) is an interference management technique well-suited to OFDMA-based cellular networks wherein the cells are partitioned into spatial regions with different Frequency Reuse factors. To date, FFR techniques have been typically been evaluated through system-level simulations using a hexagonal grid for the base station locations. This paper instead focuses on analytically evaluating the two main types of FFR deployments - Strict FFR and Soft Frequency Reuse (SFR) - using a Poisson point process to model the base station locations. The results are compared with the standard grid model and an actual urban deployment. Under reasonable special cases for modern cellular networks, our results reduce to simple closed-form expressions, which provide insight into system design guidelines and the relative merits of Strict FFR, SFR, universal Reuse, and fixed Frequency Reuse. We observe that FFR provides an increase in the sum-rate as well as the well-known benefit of improved coverage for cell-edge users. Finally, a SINR-proportional resource allocation strategy is proposed based on the analytical expressions, showing that Strict FFR provides greater overall network throughput at low traffic loads, while SFR better balances the requirements of interference reduction and resource efficiency when the traffic load is high.